Help ID this Master Cyl. please!

[Jesus_man]

This brake job has snowballed, and my MC is leaking into the cab down the rod...so I need help replacing this MC. Or figuring out if just one from a vendor will have issues. Need one ASAP as I have a trail ride in a week and I can't afford any more hiccups!

The setup is discs all the way around and I've gotten by fine with the manual brakes.

Thanks!

[D&D72]

That looks just like a stock all drum MC.

[Jesus_man]

If memory serves, that is correct. But I wanted to confirm. Is that a 1" bore?

[Gunnibronco]

Rock auto says 74 m/c is a 1" bore.

[Jesus_man]

Good news. Now to see if I can get one sourced in the next couple days...
If I went to a larger bore it would make the pedal harder correct?

[Gunnibronco]

If I went to a larger bore it would make the pedal harder correct?

Yes, I believe so.

[phyler]

Good news. Now to see if I can get one sourced in the next couple days...
If I went to a larger bore it would make the pedal harder correct?

Yes, most end up with a 1 1/16 or 1 1/8th bore from what I've gathered. The 78 Corvette master and the Lincoln masters are popular as is the f250 camper special.

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[sykanr0ng]

Good news. Now to see if I can get one sourced in the next couple days...
If I went to a larger bore it would make the pedal harder correct?

Yes, most end up with a 1 1/16 or 1 1/8th bore from what I've gathered. The 78 Corvette master and the Lincoln masters are popular as is the f250 camper special.

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The F250 Camper Special master cylinder has a 1 1/4 inch bore.

[Jesus_man]

I just hate to buy something that won't work well. I know I went thru few iterations on my last disc brake conversion before I found one that worked.

[Viperwolf1]

With no booster you may want to stay with a small piston. Yes a larger one will give you a firmer feel and less travel at the expense of more leg pressure to get stopped.

I thought the 1" bore was very good with disks and no booster. It was perfect on the street and just adequate when in low range going down hill. A bigger bore would require a stronger leg in those conditions. This was with an auto trans though.

[Jesus_man]

I decided to try the '79 F-250 Camper special which I can't confirm it's bore size at either 1" or 1-1/16". However, it was a reman and it too was leaking into the footwell past the plunger... So trying another tomorrow...urgh!

Am I doing something wrong to cause this?

I also had them bring in a stock Bronco MC as well as a backup.

[Eck]

I don’t know much about this stuff but is the push rod bent maybe pushing it in causing it to ride on one side over the other?


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[Jesus_man]

I'll look for sure, but it didn't catch my eye.

[Jesus_man]

The rod is straight. I just got a bad reman. The replacement came today and I re-installed it and after bench bleeding. It took some extra force to get the rear port to seal than I thought should be necessary, but it finally sealed. I may get some conical copper or alum. washers to seal that connection better.
http://secoseals.com/ or something similar.

I will have to return the Bronco MC and my old one as core.

[Eck]

That’s good news. It’d be nice if parts would come to us working. Seems like a tall ask anymore.


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[phyler]

JD, curious how you like the camper special master on there? Do you like the feel of the pedal?

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[Jesus_man]

Yeah it seems like a good feel for manual brakes. I've only had the pleasure of one outing but they felt like they did before and I was happy about that.

[phyler]

Yeah it seems like a good feel for manual brakes. I've only had the pleasure of one outing but they felt like they did before and I was happy about that.

Thanks! I need to replace mine. I'll look at the bore size, I would like a slightly firmer pedal than what I have now so it might be a good choice.

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[Jesus_man]

To me, it's a good happy medium between firm and soft. I really felt no difference between it and the factory one I had been running.